The general field of this invention is directed to the art of urology for achieving and maintaining internal ureteral drainage in a variety of pathologic conditions. Frequently, intubation of a ureteral stent is necessary with patients having malignant diseases, progressive azotemia and ureteral obstructions. Such obstructions are frequently caused by carcinoma of the prostate, bladder, cervix, uterus, ovary and rectosigmoid. Generally such stents are utilized on a temporary basis and are only left indwelling until a surgical procedure can be performed. Some stents on the other hand may be utilized as a permanent method of diversion and often for palliation and relief of pain.
The use of stenting catheters has been substantiated in the medical literature and in general practice. Note for example, Gibbons, R. F., Correaa, R. J., Jr., Cummings, K. B. and Mason, J. T.: "EXPERIENCE WITH INDWELLING URETERAL STENT CATHETERS" Journal of Urology, 1976 115:22 and Hepperten, Thomas W., M. D.: "SELF-RETAINED INTERNAL URETERAL STENTS: A NEW APPROACH". The Journal of Urology June 1978 119:731-734.
Indwelling ureteral stents also aid ureteral alignment and maintenance of ureteral caliber. The devices can be placed either endoscopically or utilizing open surgery to provide drainage of the kidney to the bladder when the anatomical ureter cannot adequately perform this task by itself.
Ureteral stents are shown in the prior art and emphasis in recent years has been directed to providing means associated with the stents to prevent upward or downward migration. Note for example, the patent of Gibbons, U.S. Pat. No. 3,938,529, which utilizes flexible, laterally extending barbs for this purpose. Barbs of this type, however, increase the diameter of the stent and make it more difficult to insert and in some instances can cause the stent to migrate outside the bladder creating problems for the physician. Finney, U.S. Pat. No. 4,212,304, provides a ureteral stent having opposed hook-shaped elements for retention. Devices of this type must be provided in numerous lengths to accommodate the particular patient. Additionally, note the ureteral prosthesis of Rey et al, U.S. Pat. No. 4,225,979.